The present invention relates generally to the field of computer storage and more particularly to the field of mass storage library systems.
A tape storage library system is a mass data storage system in which sometimes hundreds or thousands of tape cartridges are held in an array called a library. Each cartridge includes a storage medium (a magnetic tape), and cartridge memory (a non-volatile memory device for storing metadata pertaining to information stored on the tape). The library may be serviced by multiple tape drive units. Under direction of a controller, an accessor (transport mechanism) retrieves a tape cartridge from rest (a storage slot in the library) and delivers it to an available tape drive unit. The drive-unit mounts the cartridge, performs read and/or write operations as directed, and un-mounts the cartridge, whereupon the accessor returns it to a storage slot. A cartridge may cycle from rest, to a drive, and back again any number of times. Each time a cartridge goes through a mount/un-mount cycle, it may go to an arbitrary drive. Various blocks of data written on the tape may be written by different drives and may be read-out by different drives.